Editing Enterobacteriaceae (section)

==Historical systematics and taxonomy==
Enterobacteriaceae was originally the sole family under the order Enterobacteriales. The family contained a large array of biochemically distinct species with different ecological niches, which made biochemical descriptions difficult.<ref>{{Cite book|date=2005|editor-last=Brenner|editor-first=Don J.|editor2-last=Krieg|editor2-first=Noel R.|editor3-last=Staley|editor3-first=James T.|editor4-last=Garrity|editor4-first=George M.|editor5-last=Boone|editor5-first=David R.|editor6-last=De Vos|editor6-first=Paul|editor7-last=Goodfellow|editor7-first=Michael|editor8-last=Rainey|editor8-first=Fred A.|editor9-last=Schleifer|editor9-first=Karl-Heinz|title=Bergey's Manual® of Systematic Bacteriology|url=http://dx.doi.org/10.1007/0-387-28022-7|doi=10.1007/0-387-28022-7|isbn=978-0-387-24144-9}}</ref><ref>{{Citation|last1=Octavia|first1=Sophie|title=The Family Enterobacteriaceae|date=2014|url=http://dx.doi.org/10.1007/978-3-642-38922-1_167|work=The Prokaryotes|pages=225–286|place=Berlin, Heidelberg|publisher=Springer Berlin Heidelberg|isbn=978-3-642-38921-4|access-date=2021-06-02|last2=Lan|first2=Ruiting|doi=10.1007/978-3-642-38922-1_167}}</ref> The original classification of species to this family and order was largely based on 16S rRNA genome sequence analyses, which is known to have low discriminatory power and the results of which changes depends on the algorithm and organism information used. Despite this, the analyses still exhibited polyphyletic branching, indicating the presence of distinct subgroups within the family.<ref>{{Citation|last1=Francino|first1=M. Pilar|title=Phylogenetic Relationships of Bacteria with Special Reference to Endosymbionts and Enteric Species|date=2006|url=http://dx.doi.org/10.1007/0-387-30746-x_2|work=The Prokaryotes|pages=41–59|place=New York, NY|publisher=Springer New York|isbn=978-0-387-25496-8|access-date=2021-06-02|last2=Santos|first2=Scott R.|last3=Ochman|first3=Howard|doi=10.1007/0-387-30746-x_2}}</ref>

In 2016, the order Enterobacteriales was renamed to Enterobacterales, and divided into 7 new families, including the emended Enterobacteriaceae family.<ref name="Adeolu201622"/> This emendation restricted the family to include only those genera directly related to the type genus, which included most of the enteric species under the order. This classification was proposed based on the construction of several robust phylogenetic trees using conserved genome sequences, 16S rRNA sequences and multilocus sequence analyses. Molecular markers, specifically conserved signature indels, specific to this family were identified as evidence supporting the division independent of phylogenetic trees.

In 2017, a subsequent study using comparative phylogenomic analyses identified the presence of 6 subfamily level clades within the family Enterobacteriaceae, namely the "Escherichia clade", "Klebsiella clade", "Enterobacter clade", "Kosakonia clade", "Cronobacter clade", "Cedecea clade" and an "Enterobacteriaceae incertae sedis clade" containing species whose taxonomic placement within the family is unclear.<ref>{{Cite journal|last1=Alnajar|first1=Seema|last2=Gupta|first2=Radhey S.|date=October 2017|title=Phylogenomics and comparative genomic studies delineate six main clades within the family Enterobacteriaceae and support the reclassification of several polyphyletic members of the family|url=https://pubmed.ncbi.nlm.nih.gov/28658607/|journal=Infection, Genetics and Evolution|volume=54|pages=108–127|doi=10.1016/j.meegid.2017.06.024|issn=1567-7257|pmid=28658607|bibcode=2017InfGE..54..108A }}</ref> However, this division was not officially proposed as the subfamily rank is generally not used.